Default visibility of the properties are set in the CentLib.prp file which is the property file associated to the Central Library you point to in your project. This file can be edited graphically through Library Manager that you can launch directly from DxDesigner (Tools>Library Manager). From within Library Manager you go to Tools>Properties Definition Editor and you click on the Advanced button to see the options for the selected property (Tolerance in your case). You'll probably find out that the Visible option is set to No. Chnage it to Yes and it should do it!